Tissue elasticity is widely held as being strongly associated with disease, especially breast malignancy given[unreadable] the prominent place that physical examination holds in breast cancer screening. As a result, a sizeable[unreadable] technology effort has emerged to develop and evaluate new concepts for measuring and imaging[unreadable] parameters related to the mechanical characteristics of breast tissue. Project I, Magnetic Resonance[unreadable] Elastography (MRE), exploits phase contrast techniques to encode induced harmonic mechanical wave[unreadable] motion into phase accumulations during customized gradients to map the full displacement field in three[unreadable] dimensions from which mechanical property estimates are derived at or near the MR acquisition resolution.[unreadable] During the current funding period, Project I has successfully realized a robust MRE technique which has[unreadable] been deployed on a limited basis during clinical breast exams to demonstrate feasibility, provide preliminary[unreadable] estimates of the mechanical properties of normal breast, and highlight opportunities for extracting more[unreadable] complex mechanical behaviors. The existing MRE method is ready for systematic clinical deployment and[unreadable] will be used in a research plan consisting of (a) clinical evaluation, (b) continued technical advancement and[unreadable] (c) histopathological correlation to begin to identify the biological signatures of mechanical property contrast.[unreadable] The specific aims for continuation of Project I include (1) development of MRE driving and reconstruction[unreadable] techniques to estimate viscoelastic mechanical behavior in breast tissue, (2) Optimization of image[unreadable] acquisition sequences and methods to reduce exam time (3) exploration of shear modulus and viscoelastic[unreadable] property correlations with histopathological analyses in mastectomy specimens where adequate tissue is[unreadable] available to spatially sample and orient the imaged volume, and (4) participation in the clinical study designs[unreadable] executed by the Clinical Core targeting screening abnormalities recommended for biopsy, palpable masses[unreadable] on clinical breast exams and pilot exams of locally-advanced disease receiving neoadjuvant therapy. If[unreadable] successful, these aims are expected to generate evidence sufficient to estimate convincingly the potential of[unreadable] MRE to contribute to differential diagnosis, and pilot data in support of a role in treatment prognosis and[unreadable] therapy monitoring which will inform decisions on the initiation of larger clinical trials with MRE in the future.[unreadable]